solid lifter 30/30 cam
07-26-2006, 08:31 AM
#1
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solid lifter 30/30 cam
Does anyone now a way in wich to confirm, what we believe to be a 30/30 cam? Possibly with a dial indicator, if anyone may have the spec.And also the lash setting.
Thank you,
Rick
Thank you,
Rick
07-26-2006, 11:36 AM
#2
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Part number 3849346 has a casting number of 347, but not visible in the car obviously. The gross lift is .485 or .455 net. The lash is .030 intake and exhaust - that's why many people call it a 30/30 cam.
.485 gross lift
.030 subtact lash, then equals
.455 net lift
If you find the existing lash differs considerably from 30 thousands it's likely not a 3849346, but they have been very popular over the years.
.485 gross lift
.030 subtact lash, then equals
.455 net lift
If you find the existing lash differs considerably from 30 thousands it's likely not a 3849346, but they have been very popular over the years.
07-26-2006, 01:15 PM
#3
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Valve lift is a "theoretical" number based on a 1.5:1 rocker ratio, which is never achieved on the actual engine.
You can measure lobe lift at the rocker arm pushrod socket with a dial indicataor. The OE spec for gross lobe lift is .323", both sides.
I recommend .023" cold lash based on actual rocker ratio behavior measurments and analysis of the OE lobe data that shows the top of the constant velocity clearance ramp is .017" above the base circle. The actual lash on the drawing is .025" (.017 x 1.5). My recommended cold lash is based on the measured lash point rocker ratio of 1.37 times .017.
Lash all the inlets at 90 ATC and all the exhausts at 90 BTC.
There is a paper floating around co-written by JohnZ and me that explains all this in great detail and has lash recommendations for all the OE mechanical lifter cams. The latest revision is Dec/05. Don't use earlier versions.
Duke
You can measure lobe lift at the rocker arm pushrod socket with a dial indicataor. The OE spec for gross lobe lift is .323", both sides.
I recommend .023" cold lash based on actual rocker ratio behavior measurments and analysis of the OE lobe data that shows the top of the constant velocity clearance ramp is .017" above the base circle. The actual lash on the drawing is .025" (.017 x 1.5). My recommended cold lash is based on the measured lash point rocker ratio of 1.37 times .017.
Lash all the inlets at 90 ATC and all the exhausts at 90 BTC.
There is a paper floating around co-written by JohnZ and me that explains all this in great detail and has lash recommendations for all the OE mechanical lifter cams. The latest revision is Dec/05. Don't use earlier versions.
Duke
Last edited by SWCDuke; 07-26-2006 at 01:18 PM.
